Experiment 9: Biochemical Tests Lab Notebook
Purpose/Relevance (2 points)
. To distinguish one group of bacteria for identification purposes. Explain this further
Data/Results (24 points)
• Known Organism
• Table of each test performed, with result and appearance and color changes.
• Table of all 13 organisms with a written/illustrated description of each
The known organism was Staphylococcus epidermidis. It is a gram-positive Cocci
The following tests were performed
1)Glucose Fermentation Media color: Blue green
2)Sucrose Fermentation Media color: Blue green
3)Lactose Fermentation Media color: Blue green
4)Raffinose Fermentation Media color: Blue green
5)Mannitol Fermentation Media color: Purple
6)MacConkey Agar Media color: purple agar plate
7)Simmons Citrate Media color: green agar slant
8)MR/VP Media color: Yellow
9)Bile Esculin Media color: Tan agar slant
10)Lysine Media color: Silver
11)Indole/Tryptone Media color: Clear or yellow
12)Klingler’s/HaS Media color: orange agar Slant
13)Urease Media color: Yellow/Orange
14)Nitrate Media color: Yellow
15)Catalase Media color: Tan agar plat
Extra Lab Report Questions (10 points):
1)If isoamyl alcohol were not present in Kovac’s reagent when performing the indole test,
then what false test result might occur and why? (2 pts)
2) An MCB301 student was going to perform the urease test on a bacterium. They were
going to inoculate the test medium but noticed a precipitate had occurred in the broth. So,
they first heated the broth to 55°C to dissolve the precipitate. After cooling the broth, they
then inoculated the medium and incubated it. What effect could heat the broth have on
their results, and why? (2 pts)
3) An MCB301 student was going to perform the indole test on a bacterium. They prepared
the broth medium to grow the organism, but they used an acid hydrolysis of casein instead
of a pancreatic digest of casein. What effect could this change have on their test results, and
why? (2 pts)
4) Is urea broth medium a complex medium or not? Explain your answer (be specific). (2
pts
Experiment 9: Biochemical Tests
Purpose/Relevance
The
purpose of this experiment is to examine the metabolism of a known bacterium, S. arizonae,
using different biochemical tests. From the results of the test mediums, we are able to determine how the
reactions effected the bacterium metabolism and then use it for identification purposes.
Data/Results
Results of Biochemical Tests for S. Arizonae
Biochemical Test What it Tells Us
Result
Met Expectations? (Discussion)
A/G
Glucose
Fermentation
Carbohydrate
metabolism
0+/B
Sucrose
Fermentation
Carbohydrate
metabolism
0+
Lactose
Fermentation
Carbohydrate
metabolism
Yes, the medium changed from blue/green
to yellow with a gas bubble inside the
Durham tube. This means that both acid
and
gas had been produced, as expected.
Yes, as expected the medium turned blue
due to an alkaline reaction that was caused
by an amino acid utilizing a carbon source.
No acid or gas was produced, but growth
present at bottom of tube.
No, it was expected that acid would be
produced from the breakdown of the sugar
lactose. However, my results showed that
growth was present on the bottom, but no
acid or gas was produced. This may have
been due to the lack of oxidation of the
substrate causing little ATP to be generated
and therefore, no acid product because the
sugar didn’t ferment properly.
Partially. As expected the medium turned
blue with little growth on the bottom.
However, from the chart there should have
been little acid present, but none was
noted. This may have been due to the
alkaline end-products made from the
amino acids exceeding the amount of
acidic end products from the sugar,
Expected: (A)
0+/B
Raffinose
Fermentation
Carbohydrate
Metabolism
Expected:
(AVOUR
resulting in no acid production
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